What is
Environmental Thermodynamics?

Aluminum cans
are collected from roadsides and transported to a recycling center. A
helicopter is used to fly junk out of a wilderness area. Does nature
come out ahead in these "cleanup" activities?

Hydrogen is frequently
proposed as the clean fuel of the future. Does this make sense?

A tractorcade is
formed to protest the demise of the family farm. How does this rank
as appropriate symbolism?

A newly hired
pollution control engineer for an industrial firm makes $200,000 a
year, buys a large house in the suburbs and drives to work. How is
this person's life style related to the firm's pollution control
efforts?

Increasingly
environmentalists feel a need to reevaluate a variety of proposals
and actions once thought to be non- controversial or beneficial to
the environment. In this deeper analysis they inevitably confront
concepts of thermodynamics, a science whose very name my strike fear
into those not technically oriented. Yet, the assimilation of the
central ideas of thermodynamics is not only crucial but fairly easy
for anyone smart enough to be an environmentalist in the first place.

Before we discuss
environmental thermodynamics we need to define what thermodynamics as
such is. We find first of all that its subject matter is energy
conversion. A thermodynamic process occurs each time one form of
energy is converted into another, which includes every material
process, including mental activity. A common industrial thermodynamic
process, for example, is the conversion of the chemical energy of
fuels into heat energy of combustion, and this heat is in turn
converted to mechanical or electrical work. All natural processes
also have a thermodynamic aspect and the behavior of such diverse
objects as minerals, stars and life itself cannot be understood
without it.

The most important
contribution of thermodynamics is in determining whether a given
conceivable process is possible or not.. Thermodynamics answers this
question by making use of its famous first and second laws. The first
is the law of the conservation of energy, while the second implies
the impossibility of constructing a perpetual motion machine or the
spontaneous transfer of heat from a low to a high temperature
reservoir by a cyclic process. The latter also involves the concept
of entropy. Although energy is a quite well understood concept, that
of entropy is less so. A simple way to understand entropy is to
consider it as an index of disorder or the absence of order.
Disordered or high entropy states occur with the highest probability
because there are relatively more ways to achieve them. Thus, there
are many more ways to disorder (shuffle) a deck of cards than to
place it in an ordered array.

A fundamental concept
of thermodynamics is that of "system" vs. "surroundings".
We may, for example, be interested in a particular system consisting
of a chemical fuel, oxygen to burn it, and the combustion products,
carbon dioxide and water. But the total behavior of this system
cannot be understood without reference to the surroundings, with
which it may exchange both energy and matter. This concept is
particularly important to us because "surroundings" is here
synonymous with "environment."

The first law of
thermodynamics is simply one of bookkeeping and expresses the fact
that energy is always conserved or that any process must yield as
much energy, albeit in different form, as was put into it in the
first place. Thus, the total number of calories in the heat, sound
waves, air pollution, etc. produced by a machine must equal the
chemical energy-also in calories-placed in the fuel tank. Strangely,
this simple relation is widely ignored, particularly by pollution
control experts, who almost invariably fail to take into account all
significant energy inputs into their particular technology, and by
certain industry propagandists who are promoting some wasteful
technology.

By contrast, the
second law is the very antithesis of conservation, since it expresses
the spontaneous creation of entropy or disorder that drives the
process. Here the key word is spontaneous, since any
independent process that is possible must be thermodynamically
spontaneous, which, in this sense, means any process that does not
require help from an outside energy source. The second law states
that in such a process the total entropy (of system plus
surroundings) always increases. If the total entropy change
for any conceivable process is negative, we can be sure that it is
impossible in practice unless outside energy is brought to bear.

There is another
concept of thermodynamics known as "free energy". It is
actually energy only in a formal sense, since it simultaneously
incorporates both the energy and entropy of the system. It is
directly and simply related to the total entropy and like it is an
index of the possibility or impossibility of any process we might
conceive of. Unlike total entropy, however, it decreases
during a spontaneous process. Free energy turns out to be a
convenient way to characterize pollutants of all kinds, since these
always have more of it than their degradation products. For example,
under Earth surface conditions there is a marked decrease in free
energy when the pollutant carbon monoxide is converted to carbon
dioxide and subsequently, by reaction with calcium oxide, to harmless
carbonate minerals (limestone). It is a fact that virtually all
materials useful to modern society carry a heavy burden of free
energy-and ordinary energy as well-which they acquire as a necessary
part of the manufacturing process, or which they possess in nature,
as is the case with fuels. It is this "excess" free energy
that gives all our favorite gadgets and trinkets such great potential
as pollutants. It also forges a link of inevitability between energy
in all its technological forms and the resulting pollution.

It should be obvious
at this point that thermodynamics must have important practical as
well as philosophical implications for environmentalists. It is
sometimes implied that entropy and free energy are mysterious and
vague concepts of no use in practical affairs. Some readers may be
surprised to learn that numerical values of both quantities are
regularly tabulated and used in everyday calculations vital to
industry and every branch of science. The philosophical side of
thermodynamics stands out in the characteristic of spontaneity of all
independent energy transformations, since, if the process is truly
spontaneous, it must contain uncontrollable elements. We should then
ask ourselves to what extent technologists really control any of the
energetic processes they set in motion.

As powerful as
thermodynamics is, it shares with other successful theories the
characteristic of strict limitations. Since it depends for its
success on the statistics of large numbers, it cannot be used to
predict the behavior of individual or small numbers of atoms or
molecules. Nor does it explicitly contain time as part of its
structure, so that it cannot predict when or how rapidly a process
will occur.

Environmental
thermodynamics, like its familiar counterparts, is concerned with
energy conversions and flows. Rather than being confined to
individual machines or wholly natural processes, however, it is
concerned with the interactions of technology and the natural
world. As such it is very much concerned with human behavior and life
styles. Thus, technological energy flows are involved in their
entirety, from initial production, through consumption, and to
eventual radiation into space. Unlike industrial thermodynamics, it
does not stop with the evaluation of inputs and outputs of useful
work energy and products, but follows these products and accompanying
waste through all the devious paths and interactions in the
biosphere, its organisms and humankind itself. Consequently, it is
the science peculiarly suited to casting light on questions such as
those posed earlier as well as generalizations such as "clean"
or "soft" technological energy. Most significant, perhaps,
is that it enables us to raise and answer important questions.

Now let us return to
our examples stated at the beginning of this piece. We note first
that rejecting something (cans, bottles, refuse) into the
environment is a relatively spontaneous process (by any definition of
the word!) because the rejected material represents a highly
disordered and hence probable state. As in the case of a deck of
cards, there are many more ways to throw things away than to reclaim
them in an ordered array. Also, reclaiming them requires a
substantial input of energy. When aluminum companies speak of the
energy advantage of reclaimed aluminum cans over new cans made from
ore, they do not consider the "throw away entropy"
involved, since many of these cans are picked up from roadsides. The
energy cost of overcoming this entropy could be greatly reduced by
mandatory recycling for metal content of the cans. It might be
further reduced by retaining and cleaning the cans, thus saving their
"form energy" as well. However, in this alternative the
energy cost of cleaning would have to be balanced against the cost of
re-melting and re-forming. For similar reasons a heavy penalty is
paid for a relatively small return in cleaning up a wilderness area
by machine. The only good solution is not to pollute in the first
place.

The same reasoning
also applies to toxic chemical dumps. The greatest benefit of such
legislation as "superfund" may be not in cleaning up
existing dumps, which simply leads to more pollution, but in
suppressing the type of industrial development which inevitably
results in some form of pollution despite best efforts to control it.

The question
regarding presumed benefits of hydrogen as a fuel can be answered by
reference to ordinary thermodynamic tables. Sources of hydrogen are
natural hydrocarbons and water. Exploitation of the former is through
thermochemical technologies by which heat is used to drive chemical
reactions that yield hydrogen. In the case of a water source,
electrolytic or photolytic processes separate the hydrogen from the
oxygen in the water molecule. In all cases a huge expenditure of
energy is required to separate hydrogen from the other constituents.
This energy would likely come from a large, readily available source
such as the highly polluting fossil or nuclear power plants.
However, even if solar power were used for this purpose, it can be
shown that this energy form would also require a highly polluting
infrastructure and would degrade to pollution-prone forms on use.

Similarly, the
favorite tactic of the American Agricultural movement should not
impress environmentalists who demand consistency in their symbolism.
It has been convincingly argued (1)
that a major source of difficulties experienced by today's
farmers is overproduction, which depends upon over-mechanization (
well symbolized by large tractors!), resulting in debt, soil
degradation, etc. A technology that can't work with heavy inputs of
fossil fuels and solar energy can scarcely claim thermodynamic
efficiency, or indeed, any kind of efficiency.

Our last example, that
of the pollution control engineer, is of greatest interest here,
since it represents the officially sanctioned and endorsed solution
to industrial pollution. Also, many environmentalists would consider
the creation of this job as not only a desirable response on the part
of industry, but as a positive economic spin-off of pollution
control. Yet, the total cultural ramifications of technology-based,
energy intensive pollution control strategies are seldom given a
thought by industry, government or their critics. Some light is cast
on the underlying factors here by an important study of energy
analysts B. Hannon and R. A. Herendeen
(2) , who showed how total family energy use by consumers
rises directly with income in an almost straight line relation. Given
the correspondence between technological energy and pollution
previously identified here, it is clear that our affluent pollution
control engineer must contribute a significant increment of pollution
and that this is multiplied by other newly created jobs, not only in
industry, but in the state and federal agencies as well. Add this
culturally-derived pollution to that produced by the primary
production and the pollution control technology itself, and we see at
least the potential of a serious circularity. Finally, it must also
be remembered that by the first law the original pollution energy is
usually not eliminated by control devices, but is only transformed or
diverted elsewhere. It is unfortunate that neither industry nor
government has so far been inspired enough by thermodynamic reasoning
to seriously consider these problems.

At this point I
wouldn't blame the reader for being discouraged at the apparent
proclivity of thermodynamics to dash water on everyone's fondest
hopes. But if thermodynamic considerations are hard on naive
pollution control efforts, they will probably turn out to be lethal
to many of our most environmentally destructive technologies, old and
new, particularly if free energy outflows from them into the
environment are taken into account. This goes particularly for such
examples as the automobile-centered transportation system, stream
modification projects, nuclear power, and lately, the synfuels
industry. Although none of these monstrosities has ever been subject
to full analysis, their thermodynamic weaknesses are beginning to be
revealed in economic terms. As Georgescu-Roegen (3)
has suggested, accounting properly for all the energy and
material flows in such technologies would require a drastic revision
in our economic system. Thus thermodynamics becomes a powerful and
even necessary instrument of social change that we should welcome.